Clutch plate



Oct. ,2, 1951 w. v. THELANDER CLUTCH PLATE Original Filed Feb. 17, 1943 2 Sheets-Sheet l W l incen't' Ma Int/521%? TheZa-nder 3 heavy lubricating oil or grease, a small portion of which is indicated at 30. Gaskets, preferably of an oil resistant rubber, such as neoprene, are preferably provided between the outer marginal portions of the plates 21 and around the inner marginal portions thereof, as disclosed in my Patent 2,337,135, to seal the chamber 29 against leakage of the oil or grease 30. Stampings 3 I, as also disclosed in said patent, are riveted with the housing plates 21 to the ring [9 byrivets 25 and have the annular facing rings 32 secured thereon, as indicated at 33.

In operation, when relative movement takes place between the inner and outer portions of the clutch plate, the springs are compressed to cushion the drive. At the same time the heavy oil or grease 38 with which the cylinders Ila are filled is discharged from one end of cylinders Ila through bleeder holes 34 while some .oil or grease is simultaneously drawn into the'other end through holes 4|, so that these pumping devices add materially to the cushioning effect,

accordingly relieving the springs [5 of some of the load. The recoil action of the springs is also checked by the pistons and cylinders l6l'l, because their return to normal extended relationship is also retarded as a result of discharge of heavy oil or grease from the other end of the cylinders through holes 4| and as a result of the restriction of the bleeder holes 34 through which the heavy oil or grease must flow in refilling the cylinders [1a. In that way the secondary vibrations are absorbed and a smooth drive is obtained. In contrast to clutch plates employing friction braking means to resist the return of the parts to normal relationship after compression of the springs, the present piston and cylinder construction with the heavy grease or oil affords the desired checking action without perceptible wear on the relatively movable piston and cylinder parts inasmuch as the oil or grease serves to lubricate these parts. In addition, the oil or grease 30 serves for dampen- I ing or sound deadening. The oil or grease absorbs the primary vibrations substantially entirely, and working with the pistons and cylinders serves to substantially completely dampen secondary vibrations. The springs 15 cannot sound-off due to vibration, because they are immersed in the heavy oil or grease, and this heavy oil or grease has the same sound deadening effect upon all of the other parts with which it is in contact.

In accordance with my invention, the head end l6a of piston 40 is made sufliciently undersize to fit fairly loosely in cylinder [10,, that is to say, with more than the ordinary working clearance, and has an annular groove 35 provided therein in which is seated a ring 36 of neoprene a synthetic rubber which is impervious to oil. The seal ring 36 has an inside diameter large enough to permit slipping the ring over the end of the piston and into the groove without too much stretching and, on the other hand, small enough to insure a certain amount of pressure of the ring circumferentially on the bottom of the groove 35 when the ring is in place. The outside diameter of the seal ring is large enough in relation to the inside diameter of the bore 31 of the cylinder Ha to insure a tight sealing fit in the bore when the ring is forced into the bore and thereby compressed from a normally rectangular section to the barrel-shaped section shown in Fig. 2. It should be apparent that when the piston with the seal ring thereon is entered in the bore an improved hydraulic action is obtained, because the seal ring 33 conforms to the bore 31 in any and all positions of the piston regardless of whatever variation in shape or size there may be at one or more points. As a result, plates made in accordance with my invention may be manufactured in large quantities with reasonably good assurance of all of the plates adhering closely to a given standard of performance, and such good performance is furthermore assured for a much longer period of service, inasmuch as the size of the bleeder hole 34 in one end of the cylinder and the hole 4| in the other end are the only controlling factors in the operation of the piston and cylinder assembly, instead of being only two of many factors where a plain piston is employed, it being, of course, understood that the bleeder holes 34 and M may be reduced or increased in size in the application of clutch plates of the present invention to diifer ent makes and sizes of cars. The piston is kept substantially centered and therefore evenly spaced circumferentially with respect to the surrounding wall of the cylinder, and in that way frictional resistance to movement is reduced to a minimum and there is no appreciable wear on the piston 40 and cylinder Ila, whereas if the assembly depended upon a close Working fit of the piston in the cylinder to prevent leakage around the piston, the wear would soon make itself apparent in the poorer hydraulic action obtained and there would be meanwhiletoo much resistance to relative movement and also too much danger of the piston seizing or binding, especially if the piston expanded enough with change of temperature. The rubber seal ring gives a universal joint action in so far as accommodating itself to whatever angularity the piston might assume in the bore is concerned, and it gives the same substantially perfect sealing action regardless of whatever slight inclination the piston may assume in the bore. The side walls of the groove 35 diverge outwardly, as indicated at 39, so that the seal ring 36 can be compressed radially to barrel-shaped section to the extent indicated without being jammed into tight contact with the side walls of the groove and being thereby restrained so far as its freedom of action is concerned, this construction also allowing greater freedom and flexibility of operation of the piston in the cylinder. A counterbore 44 is provided in the open end of the cylinder Ila to receive the closure 45, which can be secured in place in any suitable or preferred manner. The hole 4! is centrally located in the other end of the cylinder Ila and the rod portion of piston 48, which is threaded, as at 43, in the head 16a extends so freely through this hole that the universal wobble motion of the piston in the cylinder mentioned, above is permitted, the area of restricted opening left between the rod and this hole being either equal to a certain fraction of or equal to the area of hole 34. It should be apparent that I may increase the size of the hole 4| or decrease the size of the piston rod 40 in addition to decreasing or increasing the size of the bleeder hole 34 to suit given requirements. This design with the double-action piston, therefore, is easily varied to suit a given application.

The construction shown in Fig. 3 is closely similar to that of Fig. 2, and, it will be understood, is also adapted for use with the springs l5 in the clutch plate of Fig. 1 as a substitute for the construction of Fig. 2. In this construction an open ended cylinder llb is'provided and the pissteem I 66 is singleacting-' and *rejsistancedo move- "i ment''is 'determinedentirely *by the resistance to 'f' 'fiow through the hole 41; in -the end wall 4 2", there rbeingsno bleeder' hole 34 as --the--other=constructi'on. -Manif'estly', the sizeof the-hole" H may be '-'ifncreased* or decreased ,1 or the-size of the piston rod lmay-be increased or'deereased, to suit-"retquirements. Thepiston-l-Gb has ,a-"loose fit-in "fthebore e'l and has 'arubber seal' ring? inthe 'fgrogve. 35thereof'operating in :the' same way'as seal-ring 'of' .Fig. 2. 'The' 'operationof this jideviceis substantiaily'thesame as that of Fig. 2. "It is believedithe foregoing description conveys v-' 1 1d' understanding pf the objects and advan- "jia'ges iof my invention. Therappended claims ffhave been drawnto "cover all legitimate 'rnodificai-t ions "and adaptations.

" Ifclaim:

' LA liquid shock' absorber'unitflxfor a friction clutch of the. typeincludinglrelatively oscillatable members between which'the'shock absorber unit is mounted-fortra-nsmitting driving force from one of said members to the other, said unit comp'rising a cylinder having a wall closing at least one end in which a central holeis provided and having a2headpdfliofionxthe other'end for abutting .one of the oscillatableclutch members,:-an -.'.nnd ersize. piston having a loose fit and: being cagrpablei oftlimited rocking motion in thescylinder, saidpiston including anrodv .portiorrrextending fzfreely through the aforesaid-central hole with a loose fit therein and having a head portion on its outer end outside the cylinder for abutting the other oscillatable clutch member, said piston having an annular groove and a resilient rubber sealing ring seated in the bottom of said groove under radial compression between the same and the walls of the cylinder to have sealing engagement therewith, the width of the outer portion of the annular groove being greater than that of the rubber sealing ring, the loose fit of the piston in the cylinder being such as to permit limited rocking action of the piston in the cylinder about said resilient rubber sealing ring, whereby to eliminate any tendency of said piston to bind in the cylinder upon application of force on said cylinder and piston along lines extending at an angle to the axis thereof upon relative oscillating motion of said clutch members, and the loose fit of the rod portion of said piston in the central hole limiting the rocking motion of the piston in the cylind.er,fand the restricted opening left in the central hole annularly of the rod portion of said piston serving as a bleeder hole for the inlet and outlet of liquid in the relative reciprocation of the piston and cylinder.

2. In a liquid dampened clutch plate comprising relatively oscillatable inner and outer members, a coiled compression spring for resistin relative rotary movement between the inner and outer members, an interfitting piston and cylinder associated with said spring and normally held in extended relation to one another by the spring, the cylinder extending axially into the spring from one end and the piston extending axially into the spring from the other end, the piston and cylinder each having an enlarged substantially circular head portion on the outer end thereof for abutment on theinnerside thereof with the adjacent ends of the spring, respectively, and transmitting pressure to the spring to compress the same in the relative rotary movement between the inner and outer members, the improvement which consists in that the cylinder has a wall closing at least the inner end in which a 6 asthma no1eesrwnsd,-ana- 'in' th'at' the piston "is undersize Withrespecittdthe bore of the cylinf fier 'and has"a loose'fit and being- -'capable of limitedirocking' motion therein, said piston having -an annular gro'oveand a resilient rubber sealing ring'*seated in' the-bottom "of-said groove underwradial compression between the same and the fcylinderwall to-centerthe piston in the cylinder and-seal the passage between-the same, the width 1(r fthe:outenportion of-the annular groove being "greater than -that'for-the rubber sealing ring, and "-theuoosefit or the piston inthecylinder permitting "limited-rocking motion of the piston in the "cylindenwith'saidnrubbersealing ring as a ful- "crum whereby to" eliminate any" tendency of said *{pistontobind-in the cyiinderupon' relative oscil- "flajtorym'otion of said" innerv and outer members with resuitantapplication of pressure on the b'cylinderand pistonalong'lines atxan angle to 0*theaxis. thereof, the'r'piston including a rod por- "'tionpxtending'freely'through the aforesaid cen- "tral-hole'with a loose fit' therein for connection "witl t'heienlarged head portion on the outer end f "thereofitheloose fit 'ofxthe rod portion of said '25fpiS1Z-On'in"thf central" hole limiting the rocking motion of theppi'ston inthecylinder, "and the restrictedopening left in; the central hole annularly ofxthe rod portion of said 'piston serving as a -"fblee'den'jholefor thefinlet and, outlet of liquid in the" relative reciprocation of the piston and J cylinder;

A liquidlshock absorber unitlfor a friction clutch bf'the' type including relatively oscillatable members between which the shock absorber unit is mounted for transmitting driving force from one of said members to the other, said unit comprising a cylinder having a wall closing one end in which a central hole is provided and having a head portion on the other end for abutting one of the oscillatable clutch members, an undersize piston having a loose fit and being capable of limited rocking motion in the cylinder, said piston including a rod portion extending freely through the aforesaid central hole with a loose fit therein and having a head portion on its outer end outside the cylinder for abutting the other oscillatable clutch member, said piston having an annular groove and a resilient rubber sealing ring seated in the bottom of said groove under radial compression between the same and the walls of the cylinder to have sealing engagement therewith, the width of the outer portion of the annular groove being greater than that of the rubber sealing ring, the loose fit of the piston in the cylinder being-such as to permit limited rocking action of the piston in the cylinder about said resilient rubber sealing ring, whereby to eliminate any tendency of said piston to bind in the cylinder upon application of force on said cylinder and piston along lines extending at an angle to the axis thereof upon relative oscillating motion of said clutch members, and the loose fit of the rod portion of said piston in the central hole limiting the rocking motion of the piston in the cylinder, and the restricted opening left in the central hole annularly of the rod portion of said piston serving as a bleeder hole for the inlet and outlet of liquid in the relative reciprocation of the piston and cylinder, said cylinder having a wall closing the other end, and means affording restricted inlet and outlet of liquid to and from that end of said cylinder upon relative reciprocation of the piston and cylinder.

4. In a liquid dampened clutch plate comprising relatively oscillatable inner and outer mem- 5-7 bers, a coiled compression spring for resisting relative rotary movement between the inner and outer members, an'interfitting piston and cylinder associated with said spring and normally held in extended relation to one another by the spring, the cylinder extending axially into the spring from one end and the pistonextending axially into the spring from the other end, the piston and cylinder each having an enlarged substantially circular head portion on the outer end thereof for abutment on the inner side thereof with the adjacent ends of the spring, respectively, and transmitting pressure to the spring to compress the same in the relative rotary movement between the inner and outer members, the improvement which consists in that the cylinder has a wall closing the inner end in which a central hole is provided, and in that thepistonuis undersize with respect to the bore of the cylinder and has a loose fit and being capable of limited rocking motion therein, said piston having an annular groove and a resilient rubber sealing ring seated in the bottom of said groove under radial compression between the same and the cylinder wall to center the piston in the cylinder and of the outer portion of the annular groove being greater than that of the rubber sealingring, and the loose fit of the piston in thew cylinder oscillatory motion of said inner and outer members with resultant application of pressure on v the cylinder and piston along lines at an angle .25 seal the passage between the same, the widtli'" permitting limited rocking motion of the piston 3 in the cylinder with said rubber sealing ring as a I to the axis thereof, the piston including a rod portion extending freely through the aforesaid central hole with a. loose fit therein for connection with the enlarged head portion on the outer end thereof, the loose fit of the rod portion of said piston in the central hole limiting the rocking motion of the piston in the cylinder, and the restricted opening left in the central hole annularly of the rod portion of said piston serving as a bleederhole for the inlet and outletof liquid in the relative reciprocation of the piston and cylinder,- the improvement consisting further in that said cylinder has a wall closing the outer end, and means affording restricted inlet and outlet of liquid to and from that end of said cylinder upon relative reciprocation of the piston and cylinder.

W. VINCENT THELANDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 879,058 Little Feb. 11, 1908 1,423,904 Blyburg -July 25, 1922 2,316,820 Thelander Apr. 20, 1943 2,360,731 Smith Oct. 17, 1944 

